Shuttling support frame for vacuum pickup

ABSTRACT

A shuttling frame to support and move a vacuum pickup from a heating furnace to a shaping station. Vacuum for the pickup is drawn through the shuttling frame. The frame slidably engages a fixed guide rail along a longitudinally extending edge and slides on a set of rolls along the opposing edge such that the frame can expand both longitudinally and transversely without buckling.

BACKGROUND OF THE INVENTION

1. Field of the Invention

This invention relates to the transfer of glass sheets and, inparticular, to a support frame for a vacuum pickup. The frame hasintegral vacuum passageways to connect the vacuum pickup to a vacuumsource through the support frame.

2a. Technical Considerations

Shaped and tempered glass sheets are widely used as side windows or rearwindows in vehicles such as automobiles or the like and to be suitablefor such applications flat glass sheets must be shaped to preciselydefined curvatures dictated by the shape and outline of the framesdefining the window openings into which the glass side or rear windowsare installed. It is also important that the side or rear windows meetstringent optical requirements and that the windows be free of opticaldefects that would tend to interfere with the clear viewing therethroughin their viewing area.

During fabrication, glass sheets intended for use as shaped windows invehicles are subjected to thermal treatment to temper the glass forstrengthening the same and increase the resistance of the shaped windowto damage resulting from impact. In addition to increasing theresistance of the glass sheet to breakage, tempering also causes theglass sheet to fracture into relatively small, smooth surfaced fragmentsthat are less injurious than the relative large, jagged fragments thatresult from the breakage of untempered glass.

The commercial production of shaped glass sheets for such purposescommonly includes heating flat sheets to the softening point of theglass, shaping the heated glass to a desired curvature and cooling thebent sheets in a controlled manner to a temperature below the annealingrange of the glass. During such treatment, a glass sheet is conveyedalong a substantially horizontal path that extends through a tunnel-typefurnace. The glass sheet is one of a series of sheets and is heated toits deformation temperature and transferred into a shaping stationadjacent the furnace, where the glass sheet is pressed between upper andlower molds. The upper mold is generally a vacuum mold that holds theheat softened glass sheet by suction. At about the same time, a transferand tempering ring having an outlined shape conforming to that desiredfor the glass sheet slightly inboard of its perimeter moves upstreaminto a position below the upper vacuum mold. Release of the vacuumdeposits the glass sheet onto the tempering ring which supports theperipheral portion of the glass while it conveys the glass sheet into acooling station for rapid cooling.

In prior art apparatus, glass sheets are lifted off the surface ofconveying rolls and into engagement with the upper vacuum mold either bybottom segmented land press surfaces situated between conveying rolls,vertically reciprocating lifting fingers, or directly by suction fromthe vacuum mold. The segmented lower mold provides a discontinuouslifting and shaping surface. The upper contours of the lower segmentedmold complement the shaping surface of the upper vacuum mold. Thesegmented bottom press surfaces may mark the lower surface of the glasssheet or may produce a ripple in the glass due to its discontinuouslifting and pressing surface. The vacuum mold is provided either with alower rigidly curved shaping surface, a deformable shaping surface or asmooth flat shaping surface that lifts the flat glass sheet by suctionthereagainst and depends on the release of the vacuum within the mold topermit the hot glass sheet to drop by gravity onto a tempering ring todevelop the shape dictated by the outline configuration of the temperingring. A process such as the latter is generally called drop forming.

When a flat glass sheet is shaped by drop forming, the maximum depth ofbend attainable depends on the glass thickness, glass temperature anddistance the glass has dropped. It is difficult to control the shape ofthin glass sheets, particularly those heated to high temperatures.

Drop forming, using deformable molds, and other press bending systemsemploying lower segmented molds provide an efficient technique forgenerating cylindrical, compound, variable radii and localizedconfigurations for simple and moderately complex patterns, where nodramatic bend geometries exist, but in order to pursue more complexgeometries such as J-shaped bends, reverses, twists, sharp radii anddeep localized bends, full surfaced pressing action is required. Fullsurface top and bottom pressing allows for complex shaping without themarking that may result from shaping with partial and discontinuouspressing surfaces.

It would be advantageous to develop a system whereby heated glass sheetscould be transferred directly from the furnace to a shaping station withupper and lower full face bending molds. In addition, a system thatwould accurately position glass sheets within the shaping station wouldbe desirable.

2b. Patents of Interest

U.S. Pat. Nos. 4,282,026; 4,361,432; 4,437,871; and 4,437,872 toMcMaster et al. each teach a drop forming apparatus wherein a hot glasssheet is engaged within a heating furnace by a stationery upper vacuumpickup positioned above the furnace conveying rolls and subsequently isdeposited on a shuttling carrier mold ring. The downwardly facingsurface of the vacuum pickup can be planar or curved. The pickup canreciprocate vertically to engage the glass, or auxiliary lifters can bepositioned between the furnace rolls and beneath the hot glass sheet tolift the glass for engagement with the vacuum pickup. The ring movesbeneath the vacuum supported glass sheet and the vacuum is terminated todrop the hot glass sheet on the ring and effect shaping. The ringsubsequently shuttles from its pickup transfer station to a quench unitthat rapidly cools the shaped glass. Throughout the operation, thevacuum pickup remains horizontally stationary within the furnace and theglass is transferred directly to a ring mold.

U.S. Pat. Nos. 4,227,908; 4,229,199; 4,229,200; 4,233,049; and 4,280,828to Seymour teach shaping glass sheets by drop forming. A heat softenedglass sheet exits a furnace and is positioned on a support bed below astationery flat vacuum pickup. The pickup lifts the glass sheet andmoves upward to allow a contoured shaping ring to be positioned underthe sheet. Vacuum is disengaged and the sheet drops on the ring. Theforce generated by the impact of the glass sheet on the ring providesthe bending force required to shape the sheet and conform it to thecontours of the ring. The patents also teach the use of auxiliaryshapers to impart additional contours in the glass sheet.

U.S. Pat. Nos. 4,221,580; 4,285,715; and 4,433,993 to Frank and4,430,110 to Frank et al. teach a horizontal press bending operationwherein heated glass sheets enter a shaping station and are lifted offthe run-in conveyor rolls by a slotted lower mold. The glass sheet ispressed between the slotted lower mold and a shaped upper vacuum mold.After pressing, the lower mold is retracted to a position beneath therun-in rolls. A shuttling tempering ring is positioned below the vacuummold and the vacuum is released so that the shaped glass is depositedonto the tempering ring. The ring subsequently transfers the shapedglass to a quenching station to temper the bent glass sheet. The uppervacuum mold can reciprocate vertically but is horizontally stationary.

U.S. Pat. No. 4,297,118 to Kellar et al. teaches a shuttling deformablevacuum mold that engages a heated glass sheet within a heating furnace.While still in the furnace, the mold deposits the shaped glass sheet ona shuttling tempering ring that is positioned beneath the mold. Afterdepositing the glass, the vacuum mold shuttles to a position outside ofthe furnace to cool prior to reentering the furnace to engage the nextglass sheet. The tempering ring transfers the glass sheet from thefurnace to a quenching station to temper the glass.

U.S. Pat. No. 4,517,001 to McMaster teaches the use of a travelingvacuum holder with a downwardly facing engaging surface to lift a heatedglass sheet and transfer the sheet onto a carrier ring mold within theheating furnace wherein the heated glass sheet is bent under the forceof gravity on the mold. The bent glass sheet is subsequently removedfrom the furnace to a quench unit to temper the bent glass.

U.S. Pat. Nos. 4,200,420 to Cathers et al. and 4,228,993 to Cathersteach a glass sheet orienting and transporting frame for use with anindustrial robot. The frame includes a plurality of sheet locating arms.The frame is positioned above the sheet and the arms locate edgeportions of the sheet. The frame thereafter moves the sheet and orientsit in a predetermined position. The locating arm moves away from theoriented sheet which is thereafter engaged by the frame and moved awayfrom the sheet orienting area.

U.S. Pat. Nos. 4,204,853 and 4,298,368 to Seymour teach alignmentdevices for positioning glass sheets on a hot gas support bed adjacentthe exit end of a furnace. Rotating conveyor rolls move the glass sheetover the support bed and urge it into contact with a locating frame. Theframe is contoured to conform to the curvature of a portion of theleading edge of the glass sheet. After alignment the glass sheet isshaped.

U.S. Pat. No. 4,228,886 to Moran teaches a position sensor wherein apair of sensors, each with multiple energy sources, e.g., a lightsource, direct the light source at a major surface of a glass sheetpositioned thereunder. A portion of the light directed at the sheet doesnot contact the sheet while another portion of the light makes contactwith and is reflected from the sheet. The reflected light passes througha lens and strikes a photo detector. Based on the amount of light thatstrikes the detector, the portion of the sheet reflecting the light fromeach sensor can be calculated and the overall orientation of the sheetcan be determined.

U.S. Pat. No. 4,364,766 to Nitschke teaches a microprocessor basedcontrol system for monitoring and controlling pairs of hot glass sheetsas they are conveyed through a heating, bending and tempering operation.The glass is conveyed through a heating furnace and as the glass pairsapproach an overhead vacuum pickup in the furnace, a photo electricsensor provides a glass sensing signal to a control computer thatcontrols the rotational velocity of different sets of furnace conveyorrolls. By controlling the roll speeds, the distance between adjacentsheets of glass pairs can be established for engagement with the vacuumpickup.

U.S. Pat. No. 4,360,374 to Nitschke teaches a glass sheet alignmentsystem whereby the roller conveyor in the vicinity of a vacuum holderincludes a roll shifter to shift sets of conveying rolls along thedirection of the glass sheet conveyance. The set of rolls is shifted inthe direction opposite to the direction of conveyance to reduce slidingof the glass sheet with respect to the vacuum holder as the glass sheetis engaged by the holder. In another embodiment, the conveying rollsnear the vacuum holder are driven by a drive separate from the remainingrolls of the conveyor and independently controlled, to position theglass. Both arrangements align the glass sheet beneath the vacuum holderto reduce the relative movement of the hot glass sheet immediately priorto its engagement with the vacuum holder.

SUMMARY OF THE INVENTION

The object of this invention is to provide a shuttling support frame fora vacuum pickup. The frame is constructed of hollow support members andhas a vacuum connecting arm extending from the support members to thepickup. Connectors link the vacuum pickup with the connecting arm so asto form a continuous passageway from the vacuum pickup to the hollowsupport member. One edge of the frame is slidably connected to a fixedlongitudinally extending rail. The opposing edge is attached to rollersthat move over a longitudinally extending track that generally parallelsthe rail. This guide arrangement allows the frame to expand bothlongitudinally and transversely as it is exposed to thermal cycling,e.g. as it shuttles from a heating furnace to a shaping station adjacentthe furnace, without warping the support frame. The frame also includesangle members suspended from the frame to support the pickup.

BRIEF DESCRIPTIONS OF THE DRAWINGS

FIG. 1 is an elevational view of the invention showing a preferredembodiment of the furnace, bending station, and cooling station.

FIG. 2 is an isometric schematic view of the invention illustrating thevacuum platen shuttle arrangement and vision sensor positioning system.

FIG. 3 is an isometric view of the vacuum platen shuttle arrangement,with portions removed for clarity.

FIG. 4 is a cross-sectional view taken along line 4--4 of FIG. 3illustrating the vacuum platen pickup and shuttle drive.

FIG. 5 is a view taken along lines 5--5 of FIG. 3 illustrating thevacuum platen pickup support frame and lifting cams.

FIG. 6 is a view taken along line 6--6 of FIG. 3 illustrating the vacuumplaten pickup support frame.

FIG. 7 is an isometric schematic view of the hydraulic circuitcontrolling the rotating cams.

FIG. 8 is an isometric view of the positioning frame of the visionsensor positioning system, with portions removed for clarity.

FIG. 9 is a cross-sectional view taken along line 9--9 of FIG. 8illustrating the hammock material support rolls and the guide rails withsupports.

FIG. 10 is a cut-away isometric view of the carriage slide assembly forthe hammock support assembly.

FIG. 11 is an isometric schematic view of the vision sensor positioningsystem illustrating various positions of the glass sheet to be shaped onthe hammock material.

FIG. 12 is an enlarged plan view of the viewing window of the camera ofthe vision sensor positioning system illustrating various positions ofthe leading edge of the glass sheet to be shaped.

DETAILED DESCRIPTION OF THE INVENTION

Referring to FIGS. 1 and 2, an apparatus for heating and shaping sheetsof materials such as glass, includes a furnace 20 through which sheetsof glass are conveyed while being heated to the glass deformationtemperature. It should be appreciated that although in the preferredembodiment, the sheet material is glass, the invention is not limited toglass and can be used with other heat softenable, deformable materials.A cooling station generally indicated at 22 for cooling the curvedsheets of glass and an unloading station (not shown) is located beyondthe cooling station 22 to the right of the furnace 20 as shown in FIGS.1 and 2. A shaping station 24 is disposed between the furnace 20 and thecooling station 22. A retrieval/positioning system 26 transfers heatedglass sheets from the furnace 20 and positions it in the shaping station24. A sheet transfer means 28, shown only in FIG. 2, located in thecooling station 22 transfers the shaped glass sheets from the shapingstation 24 to the cooling station 22.

Heat may be supplied to the furnace 20 in any convenient manner, e.g.,from gas burners or by electrical radiant heaters, or by a combinationof both, which heat supply means are well known in the art. The furnace20 includes a horizontal conveyor comprising longitudinally shapedtransversely extending conveyor rolls 30 that define a path of travelwhich extends through the furnace 20. The conveyor rolls 30 may bearranged in sections so that the speed of the different conveyorsections may be controlled and synchronized, in a manner well known inthe art, for proper movement and positioning of glass sheets through thefurnace 20. A glass sensing element 32 is located within the furnace 20to initiate a cycle of operation for bending.

The glass sensing element 32, electronic limit switches, and varioustimer circuits are provided to synchronize the operation of variouselements of the bending operation according to a predetermined sequence.

The shaping station 24 is comprised of a lower mold 34, shown in FIGS. 2and 3, and an upper mold 36, shown in FIGS. 1 and 2. The lower mold 34is a full surface mold with an upper pressing face 38 conforming inshape to the shape desired for the glass sheet to be bent. The lowermold 34 is fixed to a lower mold support platform 40 operativelyconnected to piston 42 for vertically reciprocating movement. Theplatform 40 is connected to a lower frame 44 as shown in FIG. 1 throughlower vertical guide rods 46. The upper surface 38 of the lower mold 34is preferably smoothly surfaced to avoid imparting any irregularities inthe glass sheet surface and, although not limiting to this invention, ispreferably composed of steel, meehanite, or a ceramic composite. Thismaterial provides a smoothly surfaced contour and good durabilitydespite intermittent contact with hot glass that causes rapid cyclictemperature variations over an extended period.

The upper mold 36 has an upper mounting plate 48 and an apertured lowerpress face 50. The press face 50 is shaped to be slightly less sharplybent than the shaping surface formed by the upper surface 38 of thelower mold 34. The upper vacuum mold 36 communicates through anevacuation pipe 52 with a vacuum source (not shown). Referring to FIG.1, the upper vacuum mold 36 is suitably connected through upper verticalguide rods 54 to an upper supporting frame 56 and is moveable relativethereto by an upper vertical piston 58. The evacuation pipe 52 may beconnected through a suitable valve arrangement to a source ofpressurized air (not shown) and the valves for the vacuum and pressureline may be synchronized according to a predetermined time cycle in amanner well known in the art. The upper mold 36 is preferably composedof steel, meehanite, or a ceramic composite covered with a refractorymaterial 60 such as fiberglass as is well known in the art.

The upper and lower molds are reinforced to ensure that, if required bythe shaping operation, the pressing action of the molds is perpendicularto the path of travel of the glass sheet to be shaped therebetween andthat the press faces 38 and 50 remain parallel to each other.

Referring now to FIG. 3, in order to transfer heat softened glass sheetsfrom the exit end of the furnace 20 to the shaping station 24, thepresent invention uses the retrieval/positioning system 26 that includesa shuttle frame 62 to move a vacuum platen pickup 64 from a parkposition within the exit end of the furnace 20 to an unload positionbetween the lower mold 34 and upper vacuum mold 36 of the shapingstation 24 and a vision sensor positioning system 66, to be discussedlater.

The shuttle frame 62 includes a pair of longitudinally extending supportbeams 68 and 70 interconnected by cross braces 72 and 74. The beams 68and 70 are hollow to supply vacuum to the platen pickup 64 as willdiscussed later. Fine tooth drive racks 76 and 78 are fixed to the topsurface of the beams 68 and 70 and engage drive sprockets 80 and 82respectively. Sprockets 80 and 82 are mounted on a common drive shaft 84which is driven by motor 86. Although not limiting to this invention,the motor 86 is preferably a D.C. motor with reducer. Counter 88 mountedon shaft 84 monitors its rotation to provide accurate positioning of theshuttle frame 62 as will be discussed later. Front guide 90 and rearguide 92 are mounted on the beam 68 and slidably engage guide shaft 94which parallels the beam 68. The guide shaft 94 is mounted to thebending assembly frame (not shown) and limits the movement of theshuttle frame 62 to the direction in which the glass sheet is conveyedthrough the furnace 20. Front roller 96 and rear roller 98 are mountedon the beam 70 and positioned to ride over roller guide track 100.

Because the shuttle frame 62 is exposed to high thermal conditions andextreme thermal cycling, i.e. movement from its parked position in thefurnace 20 to the unload position in the shaping station 24 and backagain, it is subject to stress conditions that may tend to bend and warpthe frame 62. The arrangement of the preferred shuttle frame 62overcomes this by providing free expansion capabilities. The only fixedreference location relative to the shuttle frame 62 is the guide shaft94. The frame 62 can expand longitudinally without warping or bindingbecause the front guide 90 and rear guide 92 on the beam 68 and thefront roller 96 and rear roller 98 on the beam 70 can each movelongitudinally relative to each other. In addition, since the rollers 96and 98 move in the track 100 and are not restricted in a lateraldirection, the shuttle frame 62 can expand or contract laterally withoutwarping or binding.

The vacuum platen pickup 64 is positioned on a free hanging frame 102between the beams 68 and 70 and cross braces 72 and 74 so that it canmove vertically, independent from the shuttle frame 62. As shown in FIG.4 the platen pickup 64 includes a flat lower apertured wall 104, sidewalls 106 and an outer perimeter ledge 108. Lid 110 rests on seat 112 ofthe side walls 106 to form an enclosed chamber 114 through which vacuumis drawn in a manner to be discussed below. Although not limited in thisinvention, the lower wall 104 is preferably, made of either ceramicmaterial or meehanite cast iron. In either instance, face 116 of thelower wall 104 is covered with a heat resistant, non-reactive,insulating, smooth surfaced material 118, such as Kaowool® 2600 paperavailable from Babcock and Wilcox. The material 118 is glued to the face116 with an adhesive that has thermal expansion properties similar tothat of the lower wall 104. Holes are then bored through the material118 to be aligned with the apertures in the lower wall 104 to providepassageways 120 through which vacuum is drawn. Other materials such asgraphite, metal oxides, boron nitride, and alumina and silica papersalso have been used to coat or cover the face 116 of the platen pickup64. The cover material 118 helps insulate the glass sheet G from thepickup 64 to reduce heat loss and permit a lower exit temperature of theglass sheet G from the furnace 20.

It should be noted that although the preferred vacuum platen pickup 64is a flat pickup, a deformable vacuum pickup similar to the deformablevacuum molds in U.S. Pat. Nos. 4,297,118 and 4,430,110 which teachingsare hereby incorporated by reference, could be used to preform theheated glass sheet prior to final bending.

As shown in FIG. 4, the preferred embodiment of the invention includesconnecting arms 122 that extend inwardly from the beams 68 and 70 of theshuttle frame 62 over the lid 110 of the platen pickup 64. The arms 122are hollow with opening 124 and extended neck section 126 to providevacuum passage between the chamber 114 and the beams 68 and 70. Heatresistant material 128 can be packed between the connecting arm 122 andthe lid 110 as well as around the neck section 126 to help reduce vacuumleakage. The connecting arm 122 is vertically spaced from the lid 108and the neck section 126 is slidably positioned within the lid 108 toallow for vertical movement of the vacuum platen pickup 64 duringoperation, as will be discussed later. As an alternative, the connectingarm 122 can be made flexible at its connection with the beams 68 and 70such as by using spring steel, spiral wrapped, heat resistant rubber, sothat the neck section 126 can be fixed to the lid 108 while theconnecting arm 122 flexes to allow for vertical movement of the platenpickup 64.

Vacuum is drawn through the passageways 120 of the apertured wall 104,through neck section 126 which extends into chamber 114, through theconnecting arm 122, through the beams 68 and 70 and out vacuum hookups130 and 132. The dead weight of the lid 110 as well as a closing actionresulting when the vacuum is drawn, helps seal the upper edge of thechamber 114. This arrangement of directing the vacuum through theshuttle frame 62 allows the vacuum hookups 130 and 132 to be connectedoutside of the furnace 20 so that they are not exposed to hightemperature conditions or thermal cycling. Furthermore, any thermaldegradation of the vacuum actuators or valves is reduced.

Referring to FIGS. 4, 5, and 6 as required, the free hanging frame 102includes a rectangular frame 134 composed of a pair of longitudinallyextending support angles 136 and a pair of laterally extending supportangles 138 suspended from lifting cams 140. The angles 136 and 138 eachhave an inwardly extending leg portions 142 and 144 respectively, tosupport the perimeter ledge 108 of the platen pickup 64. As illustratedin FIGS. 5 and 6 the angles 136 and 138 are interconnected at thecorners of the rectangular frame 134 by angles 146. Horizontal legportion 148 of the angle 146 is secured to leg portion 144 of thelaterally extending support angle 138 by bolt assembly 150. Hole 152through leg portion 144 and hole 154 through leg portion 148 are sizedlarger than the diameter of bolt 156 so as to allow slippage at thecorners of the frame 102 as it expands and contracts due to cyclicheating. Nut 158 is welded to the lower face of leg portion 144 toprevent it from falling off and damaging a conveyor roll. Vertical legportion 160 of the angle 146 is secured to vertical leg portion 162 ofthe longitudinally extending support angle 136. Vertical leg 164 of eachof the angles 138 is fitted with frame support angles 166 which ride onthe lifting cams 140. Each pair of cams 140 are interconnected by acommon cam shaft 168 and 170, supported by blocks 172 which are mountedto cross braces 72 and 74 respectively. An alignment pin 174 extendsupwards from the block 172 and through a hole 176 in the support angles166 so that the movement of the vacuum platen pickup 64 and free hangingframe 104 remains generally vertical.

As shown in FIG. 7, the cams 140 are part of a hydraulic circuit thatrotates all the cams 140 simultaneously in the same direction. Cam pair178 on cam shaft 168 and cam pair 180 on the cam shaft 170 areinterconnected by linkage 182 that includes horizontal rod 184 pinned atjoints 186 and 188 to rotating arms 190 and 192, respectively. Theopposite ends of the arms 190 and 192 are fixed to the cam shafts 168and 170. respectively. Extension 194 of the cam shaft 168 is connectedto rotating arm 196 which in turn is pinned at connection 192 tohydraulic link arm 200. Hydraulic cylinder 202 engages the link arm 200and drives it forward and backward as indicated by arrow 204. Thisaction pivots the arm 196 linked to the cam shaft 168 and causes it torotate as indicated by arrow 206. The linkage 182 which is alsoconnected to cam shaft 168, moves as indicated by arrows 208 and causescam shaft 170 to rotate as indicated by arrow 210.

In the preferred embodiment, each cam 140 is positioned in the sameorientation relative to the cam shafts 168 and 170. As a result, whenthe hydraulic cylinder 202 is activated and the cams 140 rotate, thefree hanging frame 102 supporting the platen pickup 64 moves verticallyan equal amount at each support. As can now be appreciated, the vacuumplaten pickup 64 can be made to tilt. Cams of different configurationscan be used at each support so that as the cam shafts rotate, eachcorner moves a different amount. In addition, spacers can be insertedbetween the support angles 168 and blocks 172, preferably at selectedalignment pins 174 to limit the downward movement of the frame 102 at aparticular support. Furthermore, the cams 140 can be oriented atdifferent degrees of rotation so that as the cams 140 rotatesimultaneously, one cam or one pair of cams will raise or lower theframe 102 a different amount from the other cam or pair of cams. Afourth alternative includes connecting each cam or pair of cams withindividually controlled hydraulic circuits.

The vision sensor positioning system 66 as shown in FIGS. 8, 9 and 11 islocated at the shaping station 24 to enhance the in-press positioningaccuracy of the retrieval/positioning system 26 as it deposits heatedglass sheets from the furnace 20 at the shaping station 24 for shaping,and includes a glass sheet positioning frame 212 and a vision sightingsetup 214 as shown in FIG. 11. The positioning frame 212 includes acarriage 216 mounted on the lower mold support platform 40 such thatportions of the carriage 216 can move longitudinally along the axisdefined by the direction in which the glass sheets are conveyed. Thecarriage 216 includes a guide rail and carriage support assembly 218, ahammock support assembly 220 and a carriage slide assembly 222. Thecarriage support assembly 218 includes transverse cross beams 224 arerigidly mounted to the platform 40 and support four corner posts 226.Each corner post 226 supports a guide rail pillow block 228 on avertically adjustable pedestal 230. The posts 226 are channeled toreceive finger members 232 of the pedestal 230 for vertically slideablemovement therein. The pedestal 230 can be vertically secured in positionin any well known manner such as a set screw 234 inserted through one ofthe apertures 236 in the finger member 232 and into a bore (not shown)in the corresponding post 226. Each pair of pillow blocks 228 supportsopposite ends of a carriage guide rail 238. The guide rails 238 areparallel to each other and extend in the longitudinal sliding directionof the carriage 216 as indicated by arrow 240.

The hammock support assembly 220 which slides relative to the guide railand carriage support assembly 218 includes an upper rectangular frame242 to support a hammock supply roll 244, a hammock take-up roll 246 anda pair of hammock stretching rolls 248 and 250. The hammock material 252which is a high heat resistant fabric that will not react with or markhot glass sheets supported thereon, is stretched from the supply roll244 over the stretching rolls 248 and 250 to the take-up roll 246.Although not limited in this invention, the hammock material 252 ispreferably a fiberglass cloth. The upper frame 242 is constructed oflongitudinal struts 254 and 256 connected by transverse cross beams 258and 260. Bearing blocks 262 positioned on mounting plates 264 at thecorners of the rectangular frame 242 provide rotational support at theends of shafts 266 and 268 of the hammock stretching rolls 248 and 250respectively. The supply roll 244 and take-up roll 246 are suspendedfrom the corners of the rectangular frame 242 by vertical mountingplates 270. Bearing blocks 272 are bolted to mounting plates 274 onplates 270 to provide rotational support at the ends of shaft 276 of thesupply rolls 244 and shaft 278 of the take-up roll 246. Rolls 244, 246,248 and 250, along with carriage guide rails 238, are preferably allaligned parallel to each other.

One end of each stretching roll shafts 266 and 268 extend through thebearing block 262 and is fitted with a releasable ratchet assemblies 280and 282 mounted on the mounting plate 264 to restrict the rotation ofeach stretching roll 248 and 250 to only one direction, respectively.One end of shafts 276 and 278 are similarly provided with a ratchetassemblies 284 and 286, respectively, to restrict rotation of the supplyroll 244 and take-up roll 246. With specific reference to FIGS. 8 and 9,in order to maintain the hammock material 252 taut, take-up roll 246 andsupport roll 250 are biased in a clockwise direction, while supply roll244 and support roll 248 are biased in a counterclockwise direction tostretch and tension the material 252. The respective ratchet assembliesprevent each roll from rotating in a direction to relieve the tension.If required, surface 290 of the support rolls 248 and 250 can beroughened or coated with a gritty material to help grip and stretch thehammock material 252. In the preferred operation of the apparatus, thehammock material 252 is stretched to make the glass supporting portion288 as flat as possible for reasons to be discussed later.

Rail guides 292 are mounted on the underside of struts 254 and 256 toslidably engage the rails 238 so that any longitudinal movement of thehammock support assembly 220 will be in the direction of the rails 238.

The carriage slide assembly 222 as shown in FIGS. 8 and 10 slidablymoves the hammock support assembly 220 over the stationary guide railand carriage support assembly 218. The slide assembly 222 is connectedto cross beam 258 of the hammock support assembly 220 by angle member294 which is secured to slide block assembly 296 via bent plate 298.With specific reference to FIG. 10, the slide block assembly 296includes an upper plate 300 secured to the bent plate 298 and a lowerplate 302 fixed to the lower support platform 40 through shims 304.Sliding surface 306 of the lower plate 302 includes longitudinallyextending interlocking grooves 308 which mate with the contours ofsliding surface 310 of the upper plate 300 to prevent the plates fromvertically separating while allowing them to slide relative to eachother. A cavity 312 is positioned between plates 300 and 302, extendingin the sliding direction of the upper plate 300. Threaded nut 314 isfixed within upper surface of the cavity 312 to the upper plate 300 andspaced from the lower surface of the cavity 312 at lower plate 302. Athreaded shaft 316 extending from a drive 318, which is fixed to thelower plate 302 or the platform 40, passes through and engages the nut314 so that as the threaded shaft 316 rotates within the threaded nut314, the upper plate 300 slides in a linear direction relative to thelower plate 302 as indicated by arrow 320.

It should be noted that while the present invention employs a slidingarrangement that moves the glass sheet positioning frame 212 in alongitudinal direction, an arrangement that would also provide lateraladjustment and rotational adjustment about a vertical axis could be usedand in light of the present disclosure such an arrangement would beobvious to one skilled in the art.

With reference to FIG. 11, the vision sighting setup 214 of the visionsensor positioning system 66 is employed to physically locate a glasssheet that is on the hammock support assembly 220 and control thecarriage slide assembly 222 to move the hammock supported glass sheet toa predetermined position between the pressing molds in the shapingstation 24. The setup 214 includes a solid state video camera 322 linkedto a vision system programmable computer and controller 324. The camera322 is positioned such that it can view a generally transverselyextending edge of a glass sheet deposited on the hammock supportassembly 220. The camera 322 has a preferred array of approximately 250by 250 picture elements or pixels. Each pixel is one point in theviewing array and is viewed as either a black or a white image. In thepreferred embodiment, the leading edge of the glass sheet G to be shapedis illuminated such that the pixels are covered by the glass sheet areviewed as black while the uncovered pixels are viewed as white. In analternate embodiment, the camera 322 can be used to locate the glasssheet by detecting infrared radiation radiating from the heated glasssheet.

In operation, a home position representing the proper location for areference point on the glass edge is established in the pixel array. Aseach successive glass sheet is deposited on the hammock material 252 andthe vacuum shuttle frame 62 moves out of the camera 322 viewing area andback into the furnace 20, the camera 322 takes an instantaneous pictureof the glass edge showing the location of the reference point. Thisinformation is sent to the programmable computer and controller 324which compares the actual position of the reference point to the homeposition and calculates the distance the glass sheet must be moved inthe sliding directing of the hammock support assembly 220 to be properlyaligned. The computer and controller 324 then sends a signal through asignal amplifier 326 to the drive 318 which moves the upper plate 300 ofthe carriage drive assembly 222 forward or backward to properly positionthe glass sheet. The viewing of the glass sheet G and movement of thehammock support assembly 220 occurs before or while the upper and lowermolds are moving towards one another, depending on the amount ofmovement required to align the glass sheet G, and is completed prior tothe actual pressing operation. After the shaped glass sheet is liftedoff the hammock 252 by the upper vacuum mold 36, the carriage slideassembly 222 slides back to its original position and the vision sensorpositioning system 66 is reset for the next glass sheet.

In the preferred operation of the positioning system 66, the viewingarea of the camera 322 is limited to a 11/2" by 1/4" (3.81 cm by 0.64cm) longitudinally extending viewing window 328 as shown in FIG. 12. Inaddition, three references points A, B, and C are viewed by the camera322 to position the glass sheet. After the camera 322 takes a picture ofthe glass sheet edge, the pixel positions for each point is located andthese positions are averaged. This average position is compared to thepredetermined home position to determine the amount of sliding movementrequired by the carriage slide assembly 222. Referring to FIGS. 11 and12, reference outline 330 with leading edge 332 illustrates thepredetermined home position, with a glass sheet 334 located slightlyupstream and the glass sheet 336 slightly downstream from the homeposition. In the case of the upstream glass sheet 334, after the averageposition of points A, B and C is determined, the hammock supportassembly 220 is moved downstream in the direction indicated by arrow 338so that leading edge 340 is superimposed over the leading edge 332 ofthe reference outline 330. In the case of downstream glass sheet 336,the hammock support assembly 220 moves upstream in the directionindicated by arrow 342 so that leading edge 344 is superimposed over theleading edge 332.

In the preferred embodiment of the invention, the motor 318 (see FIG.10) is a stepper motor so that the programmable computer and controller324 must determine the correct number of rotating steps to properlyposition the glass sheet G between the molds in the pressing station 24.The positioning accuracy of the vision sensor position system 66 is±0.010 inches (±0.025 cm).

It is contemplated that the shuttling vacuum platen pickup 64 canoperate with or without the vision sensor positioning system 66. Whenthe system 66 is not employed, the pickup 64 deposits the heat softenedglass sheets directly on the lower mold 34 or on a stationery glasssupport assembly similar to the hammock support assembly 220 of thepositioning 212 but without the carriage slide assembly 222.

It should be noted that in practicing this invention, successive contactwith and support of the hot glass sheets generally weaken the hammockmaterial 252. In addition, the material becomes discolored and thisdiscoloration can effect the vision sighting positioning system 66 bycausing camera 322 to misidentify the edge of the glass sheet G. Toovercome these problems, the hammock material 252 is periodicallyadvanced by unlocking the racket assembles 280, 282, 284, and 286,indexing the supply roll 244 and take up roll 246, re-engaging therackets and stretching the material 252 taut. Rather than manuallyadvancing the hammock material 252, it is readily apparent to oneskilled in the art that a simple hammock roll advancing system (notshown) can be used to automatically index the rolls 244, 246, 248 and250.

The sheet transfer means 28 at the cooling station 22 includes aring-like member 346 similar to that in U.S. Pat. No. 4,285,715, whoseteachings are hereby incorporated by reference, and is shown in FIGS. 1and 2. The ring-like member 346 includes a support rail 348 that isdisposed edgewise with its edge forming the supporting surface of themember 346. The rail 348 follows the contours of the shaped glass sheetand is spaced slightly inboard of the glass sheet perimeter. The glasssheet supporting surface of the rail 348 is preferably a nonmetallicmaterial that can support the hot glass sheet without leaving a mark onthe glass sheet surface or cause venting. The ring-like member 346 issupported by a reinforcing frame 350 and connected to a carriage 352 bystrut members 354. The carriage 352 moves the member 346 from anupstream position wherein the member 346 is positioned in a shapingstation 24 beneath the upper vacuum mold 36 to a downstream positionwherein the member 346 is positioned between quenching nozzles in thecooling station 22.

The cooling station 22, which is similar to that taught in U.S. Pat. No.4,285,715, includes longitudinally spaced transverse rows of spaced pipenozzles 356 extending downward from an upper plenum 358 as shown inFIGS. 1 and 2. In opposing position to nozzles 356 are longitudinallyspaced transversely extending lower bar type nozzle houses 360 on lowerplenum 362. The bar type nozzle housings 360 are spaced vertically belowthe upper pipe nozzles 356 to provide clearance for moving the ring-likemember 346 along a path therebetween. The lower ends of the rows of thepipe nozzles 356 are located along a curved surface complimentary to thecurved shape of the upper smooth surfaces of the bar-type housings 360and are vertically spaced above the housing 360 to provide a curvedclearance space between conforming to the transverse shape of the glasssheet conveyed therebetween. If desired, the plenums 358 and 362 can besectionalized along the length of the cooling station 22 to providedifferent air pressures in the various sections of the upper plenum andof the lower plenum, and to provide a program of air blasts along thelength of the cooling station 22.

In the preferred embodiment of the invention, the operating sequence iscontrolled by a Modicon Programmable Controller. A G.E. ProgrammableController is linked to the Modicon to control the glass sheet alignmentsequence. In operation, a glass sheet G is conveyed through the furnace20 over the conveying rolls 30 and heated to its heat softeningtemperature. In the preferred embodiment the glass sheet G is heated toapproximately 1200° F. ±(649° C.) depending on the difficulty of thebend. The glass sheet G activates the sensing element 32 and initiatesthe shaping sequence. In the preferred embodiment, the sensing element32 is an optical sensor that starts the shaping sequence when thetrailing edge of the glass sheet G passes the sensor by activating atimer and counter. The counter monitors the revolution of conveyingrolls transferring the glass sheet G to establish its linear position inthe conveying direction. The glass sheet G enters a high speed conveyorroll complement 364 to position the heat softened glass sheet G beneaththe vacuum platen pickup 64 on the shuttle frame 62 which is in its parkposition at the exit end of the furnace 20. The platen pickup 64 is in araised position with its lower apertured wall 104 approximately 1/2 inchto 3/4 inches (1.27 cm to 1.91 cm) above the upper surface of the glasssheet G. The high speed conveyor roll complement 364 includes a "creep"or slow speed conveying mode controlled by the timer, activated by thesensor 32, to decelerate the glass sheet G and move it into positionbelow the raised platen 64 at a slow speed. As the glass sheet Gapproaches the pickup point, the timer opens a vacuum valve (not shown)so that vacuum is drawn through the platen pickup 64 and to ensure thatthe desired vacuum is at full operating levels prior to engagement ofthe glass sheet G by the pickup 64. When the glass sheet G is at apredetermined location as set by the counter, the hydraulic circuit isactivated and rotates the cams 140 to drop the free hanging frame 102supporting the pickup 64 to a lowered position, which is preferably aminimum of 3/32 inches (0.24 cm) above the upper surface of the glasssheet G. The initial vacuum level is set at a level that will not liftthe glass sheet G when the pickup 64 is in a raised position, but willlift the glass sheet G when the pickup 64 is in a lowered position.Depending on the configuration and thickness of the glass sheet G, therequired vacuum level varies from approximately 11/2 inches to 2 inches(3.81 cm to 5.08 cm) of water. The glass sheet G is lifted by suctioninto contact with the platen pickup 64. The lifting action of the platen64 is almost instantaneous and although the preferred embodiment employsa creep mode prior to lifting, it is believed that the vacuum platenpickup 64 could accurately lift a heat softened glass sheet directlyfrom a high speed roll complement.

After the glass sheet G is lifted and engaged by the pickup 64, theshuttle frame 62 is moved into the shaping station 64 via the driveracks 76 and 78, drive sprockets 80 and 82, and motor 86. As the shuttleframe 62 moves towards the unload position at the shaping station 24,the hydraulic circuit simultaneously rotates the cams 140 back towardstheir original position, lifting the free hanging frame 102, platenpickup 64 and the glass sheet G as they exit the furnace 20 to provideadditional clearance between the glass sheet G and the conveyor rolls364. If required, the vacuum in the platen pickup 64 is reduced duringshuttling to the minimum level required to hold the glass sheet G. Thisthrottling back of the vacuum helps eliminate any marking to the glasssurface that may result from the vacuum suction.

The counter 88 on drive shaft 84 is a multifunction counter andestablishes the deceleration and positioning of the shuttle frame 62 asit moves from the furnace 20 to the shaping station 24 and visa versa.As the counter 88 reaches the predetermined deceleration and stop count,it signals the Modicon to slow the platen pickup 64 with the adheredglass sheet G and stop it, respectively.

When the shuttle frame 62 is at the predetermined position between thelower mold 34 and upper vacuum mold 36, the counter 88 starts a vacuumcutoff timer. When the vacuum cutoff timer times out, the vacuum isreleased, and the glass sheet G is deposited on the fiberglass cloth 252of the hammock support assembly 220. After a short delay to ensure thatthe glass sheet G has dropped, the shuttle frame 62 reverses directionand travels back into the furnace 20 to its parked position.

The glass sheet G on the hammock support assembly 220 tends to conformto the sag of the fiberglass cloth 252. The sagging of the glass sheet Gshould be kept to a minimum in order to prevent the glass sheet G fromsagging into the lower mold 34 before the vision sensor positioningsystem 66 can reposition it prior to pressing. To minimize sag, thefiberglass cloth 252, is tightly stretched between rolls 248 and 250.

As the shuttle frame 62 moves back to the furnace 20, the camera 322"takes a picture" of the leading edge of the hot glass sheet G. If theedge is not at the predetermined home position on the fiberglass cloth252, the programmable controller 324 linked to the camera 322 activatesthe motor 318 of the carriage slide assembly 222 to move the upper plate300 over the lower plate 302 and longitudinally slide hammock supportassembly 220 as previously discussed, so that the glass sheet G isdirectly positioned between the pressing molds. Simultaneously with thesliding action, the lower mold 34 and the upper vacuum mold 36 rapidlyaccelerate towards one another with the supported glass sheet Gtherebetween. Hydraulically controlled deceleration ramps are used toslow down the movement of the molds prior to final pressing to providemore control during the critical pressing action. It should be notedthat the hammock support assembly 220 moves vertically along with thelower mold 34 and that the upper mold 36 presses down through thehammock support assembly 220 and into the lower mold 34. The stretchingof the hammock material 252 as the upper vacuum mold 36 presses theglass sheet G down into the lower mold 34 prematurely wears the material252, reducing it effective service life, especially in parts with sharpcorners. To reduce this wear, the previously discussed hammock rollsadvancing system could be modified to untension the hammock material 252to coincide with the pressing of the glass sheet G between the molds 34and 36.

During pressing, vacuum is supplied to the vacuum chamber of the uppervacuum mold 36 to hold the shaped glass sheet G against the aperturedlower wall 50 so that the glass sheet G will remain in contact with thelower wall 50 when the lower mold 34 is retracted. After a mold presstimer controlling the amount of time the molds 34 and 36 press the glasssheet G times out, the molds retract with suction still being applied tohold the glass sheet G against the upper vacuum mold 36. Shaping station24 is now ready to receive the ring-like member 346. After a carriagedelay timer activated as the mold press timer times out, the member 348moves upstream from the cooling station 22 and is positioned beneath theupper vacuum mold 36. When the member 346 is in position, the vacuum inthe upper mold 36 is released, permitting the shaped glass sheet G to bedeposited onto the member 346.

The glass sheet G is transferred downstream to the cooling station 22where it is quenched to impart at least a partial temper in the shapedglass sheet. The glass sheet G is then transferred to a cooling conveyor(not shown) for further cooling.

The movement of the shuttle frame 62, the hammock support assembly 220,the molds 34 and 36 and the ring-like member 346 are synchronized sothat there is no interference between their respective operations.Ideally, the camera 322 sights the edge of the sheet G as soon as theshuttle frame 62 moves out of its line of sight and the alignment of thesheet G immediately follows. The alignment must be complete before themolds 34 and 36 make pressing contact with the sheet G. Furthermore themolds 34 and 36 can be moving prior to the shuttle frame 62 moving outof the shaping station 24 as long as the frame 62 and molds 34 and 36 donot interfere with each others respective movement. Similarly the member346 can start to move from the cooling station 22 towards the shapingstation 24 before there is adequate room for the member 346 between themolds 34 and 36 as long as the molds are sufficiently spaced apart whenthe member 346 arrives. Limit switches (not shown) positioned along thevertical paths of the molds 34 and 36 and/or the horizontal paths of theshuttle frame 62 and ring-like member 346 can be used to ensure that theoperation sequence proceeds without interference.

The heating and shaping apparatus of the present invention provides amethod of transferring glass sheet G from a furnace 20 to a shapingstation 24 with full face upper and lower molds. The molds provide fullsurface contact between the glass sheets and the shaping surfaces tofacilitate the complex shaping of heat softened glass sheets that is notpossible when using drop forming, deformable molds, or segmented lowerlifting mold techniques. The combination of the shuttling vacuum platenpickup 64 with the vision sensor positioning system 66 provide theretrieval/positioning system 26 with a method of rapidly moving glasssheets and accurately positioning the sheets between the upper and lowermolds so as to correct for all upstream linear positioning variations.Without the present invention, glass sheets conveying rates must bereduced prior to each transfer operation to ensure proper glass sheetpositioning after the transfer. With the present invention, transferaccuracy is sacrificed for conveying speed. At the final transfer fromthe furnace 20 to the shaping station 24, the present invention detectsand determines the cumulative linear misalignment immediately prior tofinal pressing and corrects it. This capability adds to the throughputof a glass sheet bending process by allowing glass sheets to be conveyedand transferred at higher rates. These faster conveying rates may add tothe cumulative linear misalignment but the present system corrects allthe linear misalignment in one step. The final realignment takes lesstime than the total conveying and transfer time saved by increasing theconveying rate.

The form of the invention shown and described in this disclosurerepresents an illustrative preferred embodiment thereof. It isunderstood that the gist of the invention is defined in the claimedsubject matter which follows and that various modifications of thisinvention which become obvious in light of a reading of the descriptionof this specification are incorporated therein.

We claim:
 1. A support frame for a vacuum pickup comprising:supportmeans including an enclosed vacuum passageway; means to support saidpickup from said support means; means to connect said passageway in saidsupport means with said pickup such that said pickup, support means, andpassageway of said support means are interconnected by a continuousvacuum passage; means to horizontally transfer said support means andpickup from a first position to a second position; and means to guidesaid support means and pickup as said transfer means move said supportmeans and pickup.
 2. The support frame as in claim 1 wherein saidconnecting means includes at least one vacuum connecting arm extendingfrom said passageway of said support means and terminating in closeproximity to said pickup.
 3. The support frame as in claim 2 furtherincluding means to couple said passageway of said support means with avacuum source.
 4. The support frame as in claim 3 wherein said transfermeans moves said support frame and pickup from a first location within aheating cavity to second location outside said heating cavity.
 5. Thesupport frame as in claim 3 wherein said guide means includes at leastone guide member along one longitudinally extending edge of said frame,slidably connected to a fixed, longitudinally extending guide rail, andat least one roller member mounted on the opposite longitudinallyextending side of said frame for rolling movement over a longitudinallyextending track, said track being generally parallel to said guide rail,such that said frame can expand both longitudinally and transversely dueto variations in the thermal environment without warping said frame, assaid frame moves from said first position within said furnace to saidsecond position outside said furnace.
 6. The support frame as in claim 5wherein said longitudinally extending support members are external tosaid heating cavity when said support frame is in said first position.7. The support frame as in claim 6 wherein said pickup includes anoutwardly extending peripheral ledge and further wherein said supportmeans includes a plurality of angle members secured to said supportframe and positioned around the perimeter of said pickup to support saidpickup along said peripheral ledge.
 8. The support frame as in claim 7further including means to vertically move said pickup relative to saidsupport frame.
 9. The support frame as in claim 8 wherein saidconnecting arm is flexible so as to maintain connecting contact withsaid pickup throughout the vertical movement range of said pickup. 10.The support frame as in claim 9 wherein said support means includes atleast one hollow longitudinally extending support member, said supportmember providing said passageway.
 11. The support frame as in claim 9wherein said support means includes a pair of hollow, longitudinallyextending support members and said coupling means is connected to bothsupport members and further including vacuum connecting arms extendingfrom both of said support member and connecting means such that saidpickup, connecting means, connecting arms, and hollow support membersare interconnected by a continuous passage.
 12. The support frame as inclaim 11 wherein said pickup has a generally planar upwardly facingsurface and said connecting arm extends from said hollow member oversaid upwardly facing surface such that said connecting arm is adjacentto and spaced from said pickup.
 13. The support frame as in claim 12wherein said connecting arms are flexible so as to maintain connectingcontact with said pickup throughout the vertical movement range of saidpickup.